High Performance Foundation Technology: Insulating Concrete Forms (ICF).

High Performance Foundation Technology: Insulating Concrete Forms (ICF).

We are building our foundation walls using Insulating Concrete Forms (ICF) which are rigid plastic foam (EPS – Expanded Polystryrene) forms that hold concrete in place during curing. The ICFs remain in place to serve as thermal insulation for the concrete foundation walls.  These ICFs are made by Greenblock and have an R-value of about 22.

The ICFs have plastic webs every six inches for strength and for tying the two walls of EPS foam together. Rebar is placed and tied to the webs as we place layers of ICF blocks together… kind of like Legos!

Once the concrete has cured, ICFs form an incredibly strong structure that is permanent and durable. Since the protective insulation provides an ideal curing environment, tests conducted by the Portland Cement Association have shown that concrete is up to 50% stronger than concrete cured in traditional wood form systems.

We brace as we stack anticipating the pressure from the concrete pour. The ICF’s will be pumped full with a soupy concrete mixture held to a 5″-6″ slump.

Pre-manufactured 45- and 90-degree corners and a precision alignment system helps to adjust the walls to ensure a perfectly square and plumb structure.

The same system is used for the attached garage.

Our crew has laid rebar horizontally and vertically inside the ICF’s to create a structurally sound unit designed for the expected vertical and lateral loading conditions according to the structural engineer’s specs. This is earthquake country so there is lots of steel!

It’s time to call for the concrete.